C# Windows 表单 - 我如何运行我在不同线程上导出到 excel 以及我在哪里包含进度条的代码？

Question

我有时会在数据网格视图中看到超过 100000 行，我希望用户能够更快地将它们导出到 excel。目前，我的 windows 表单处于 "Not Responding" 阶段，但它实际上是在后端执行导出。我想在不同的线程上执行导出以便更快，并且我想添加一个进度条来显示导出本身的进度。

我尝试了以下方法：

创建新任务 - 导出时间实际上变长了
使用 Thread thread = new Thread(Export) 创建与运行不同的线程 - 当显示对话框行为运行

我的代码如下：

 private void BtnSearchExportCSV_Click(object sender, EventArgs e)
    {
        Export();
    }

    private void CopyAllToClipBoard()
    {
        dgvSearchFilter.ClipboardCopyMode = DataGridViewClipboardCopyMode.EnableAlwaysIncludeHeaderText;
        dgvSearchFilter.MultiSelect = true;
        dgvSearchFilter.RowHeadersVisible = false;
        dgvSearchFilter.SelectAll();

        DataObject dataObj = dgvSearchFilter.GetClipboardContent();
        if (dataObj != null)
        {
            Invoke((Action)(() => { Clipboard.SetDataObject(dataObj); }));
            //Clipboard.SetDataObject(dataObj);
        }
    }

    private void releaseObject(object obj)
    {
        try
        {
            System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
            obj = null;
        }
        catch (Exception ex)
        {
            obj = null;
            MessageBox.Show("Exception Occurred while releasing object " + ex.ToString());
        }
        finally
        {
            GC.Collect();
        }
    }

    private void Export()
    {
        try
        {
            SaveFileDialog sfd = new SaveFileDialog();
            sfd.Filter = "Excel Documents (*.xls)|*.xls";
            sfd.FileName = "Export.xls";
            if (sfd.ShowDialog() == DialogResult.OK)
            {
                // Copy DataGridView results to clipboard
                CopyAllToClipBoard();

                object misValue = System.Reflection.Missing.Value;
                Excel.Application xlexcel = new Excel.Application();
                // Without this you will get two confirm overwrite prompts
                xlexcel.DisplayAlerts = false;
                Excel.Workbook xlWorkBook = xlexcel.Workbooks.Add(misValue);
                Excel.Worksheet xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);
                // Paste clipboard results to worksheet range
                Excel.Range CR = (Excel.Range)xlWorkSheet.Cells[1, 1];
                CR.Select();
                xlWorkSheet.PasteSpecial(CR, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, true);

                // For some reason column A is always blank in the worksheet. ¯\_(ツ)_/¯
                // Delete blank column A and select cell A1
                //Excel.Range delRng = xlWorkSheet.get_Range("A:A").Cells;
                //delRng.Delete(Type.Missing);
                //xlWorkSheet.get_Range("A1").Select();

                // Save the excel file under the captured location from the SaveFileDialog
                xlWorkBook.SaveAs(sfd.FileName, Excel.XlFileFormat.xlWorkbookNormal, misValue, misValue, misValue, misValue, Excel.XlSaveAsAccessMode.xlExclusive, misValue, misValue, misValue, misValue, misValue);
                xlexcel.DisplayAlerts = true;
                xlWorkBook.Close(true, misValue, misValue);
                xlexcel.Quit();

                releaseObject(xlWorkSheet);
                releaseObject(xlWorkBook);
                releaseObject(xlexcel);

                // Clear Clipboard and DataGridView selection
                Clipboard.Clear();
                dgvSearchFilter.ClearSelection();

                // Open the newly saved excel file
                if (File.Exists(sfd.FileName))
                    System.Diagnostics.Process.Start(sfd.FileName);
            }
        }
        catch (Exception exception)
        {
            MessageBox.Show("The following exception occurred: " + exception.ToString());
        }
    }
}

我对 C# 越来越熟悉了。不过，我还是第一次遇到这样的事情。

谢谢。

Answer 1

将您的操作移至另一个线程不会使其更快，但它不会再阻塞 UI。用户不会看到 "unresponsive application".

因为您的代码是由 Button.Click 触发的，而运行是由 UI 线程触发的。如果您的操作需要时间，您的 UI 将被您的操作阻塞。
不要将UI代码SaveFileDialog和操作逻辑混在一起。
尽早使用 return 会提高代码的可读性。它减少了嵌套语句的大小。你可以 google 得到它。
System.Threading.ThreadStateException 发生是因为您在线程中使用了 SaveFileDialog 和 ClipBoard。要解决此问题，您需要将这两个函数从 Thread 调用函数中移出。如果你真的想让它工作。以下可能会使它起作用。但是我不建议这种实现方式。
```
Thread op = new Thread( operation );
op.SetApartmentState( ApartmentState.STA );
op.Start();
```

下面的示例，包括您放置进度的位置 window:

private void Export()
{
  // Do UI check first
  SaveFileDialog sfd = new SaveFileDialog();
  sfd.Filter = "Excel Documents (*.xls)|*.xls";
  sfd.FileName = "Export.xls";

  // If failed , early return
  if (sfd.ShowDialog() != DialogResult.OK)
  {
    return;
  }
  ProgressWindow prg = new ProgressWindow();
  prg.Show();
  // Do your copy and export code below, you may use task or thread if you don't want to let current form unresponsive.
  operation();
  // After finished, close your progress window
  prg.Close();
}

void operation()
{
     // Copy DataGridView results to clipboard
     CopyAllToClipBoard();

     object misValue = System.Reflection.Missing.Value;
     Excel.Application xlexcel = new Excel.Application();
     // Without this you will get two confirm overwrite prompts
     xlexcel.DisplayAlerts = false;
     Excel.Workbook xlWorkBook = xlexcel.Workbooks.Add(misValue);
     Excel.Worksheet xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);
     // Paste clipboard results to worksheet range
     Excel.Range CR = (Excel.Range)xlWorkSheet.Cells[1, 1];
     CR.Select();
     xlWorkSheet.PasteSpecial(CR, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, true);

     // For some reason column A is always blank in the worksheet. ¯\_(ツ)_/¯
     // Delete blank column A and select cell A1
     //Excel.Range delRng = xlWorkSheet.get_Range("A:A").Cells;
     //delRng.Delete(Type.Missing);
     //xlWorkSheet.get_Range("A1").Select();

     // Save the excel file under the captured location from the SaveFileDialog
     xlWorkBook.SaveAs(sfd.FileName, Excel.XlFileFormat.xlWorkbookNormal, misValue, misValue, misValue, misValue, Excel.XlSaveAsAccessMode.xlExclusive, misValue, misValue, misValue, misValue, misValue);
     xlexcel.DisplayAlerts = true;
     xlWorkBook.Close(true, misValue, misValue);
     xlexcel.Quit();

     releaseObject(xlWorkSheet);
     releaseObject(xlWorkBook);
     releaseObject(xlexcel);

     // Clear Clipboard and DataGridView selection
     Clipboard.Clear();
     dgvSearchFilter.ClearSelection();

     // Open the newly saved excel file
     if (File.Exists(sfd.FileName))
         System.Diagnostics.Process.Start(sfd.FileName);
}

根据您的描述，ProgressWindow 可能是 Form without "close" button.

Answer 2

所以我一直在四处走动，尝试不同的方法和代码，并实现了我自己的代码。到目前为止，我遇到（和修改）的最成功和最快速的代码如下：

        var headers = dgvSearchFilter.Columns.Cast<DataGridViewColumn>();
        string delimiter = ",";
        DataTable dt = new DataTable();
        foreach (DataGridViewColumn col in dgvSearchFilter.Columns)
        {
            dt.Columns.Add(new DataColumn(col.Name, typeof(string)));
        }

        foreach (DataGridViewRow row in dgvSearchFilter.Rows)
        {
            DataRow dataRow = dt.NewRow();
            foreach (DataGridViewCell cell in row.Cells)
            {
                if (row.Cells[cell.ColumnIndex].Value == null || row.Cells[cell.ColumnIndex].Value == DBNull.Value || String.IsNullOrWhiteSpace(row.Cells[cell.ColumnIndex].Value.ToString()))
                {
                    dataRow[cell.ColumnIndex] = " ";
                }
                else
                {
                    dataRow[cell.ColumnIndex] = cell.Value.ToString();
                }
            }
            dt.Rows.Add(dataRow);
        }

        string unique = DateTime.Now.ToString("yyyyMMddHHmmssffff");
        string fileName = "SQLQueryOutput_" + unique + ".csv";
        using (StreamWriter swr = new StreamWriter(File.Open(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), fileName), FileMode.CreateNew), Encoding.Default, 1000000))
        {
            swr.WriteLine(string.Join(",", headers.Select(column => "\"" + column.HeaderText + "\"").ToArray()));
            foreach (DataRow dr in dt.Rows)
            {
                var line = dr.ItemArray.Select(r => r.ToString().Contains(delimiter) || r.ToString().Contains("\n") ? "\"" + r + "\"" : r);
                swr.WriteLine(string.Join(delimiter, line));
            }
        }

        MessageBox.Show("Your file was generated and its ready for use.");

这不是 excel 格式，它是 CSV。但是，您可以在不同的线程上使用它。它会在您的桌面上生成一个带有 name_uniqueValue 的 CSV。

基本上，您将数据网格视图的列转换为逗号分隔值。然后将它们添加到 DataTable 中。一个接一个地循环遍历 DataGridView 并将值添加到 DataTable。然后使用 StreamWriter 将这些值写入 CSV。 almost/less 超过一分钟的 100 万行。

所有想要将 DataGridView 转换为 CSV 的人都可以尝试一下。

C# Windows 表单 - 我如何运行我在不同线程上导出到 excel 以及我在哪里包含进度条的代码？

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C# Windows 表单 - 我如何 运行 我在不同线程上导出到 excel 以及我在哪里包含进度条的代码？

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C# Windows 表单 - 我如何运行我在不同线程上导出到 excel 以及我在哪里包含进度条的代码？